In diesel engines, air is drawn into a combustion chamber during an intake stroke by opening one or more intake valves. Then, during the subsequent compression stroke, the intake valves are closed, and a reciprocating piston of the combustion chamber compresses the gases admitted during the intake stroke, increasing the temperature of the gases in the combustion chamber. Fuel is then injected into the hot, compressed gas mixture in the combustion chamber, resulting in combustion of the fuel. Thus, in a diesel engine, the fuel may combust with the air in the combustion chamber due to the high temperature of the air, and may not be ignited via a spark plug as in a gasoline engine. The combusting air-fuel mixture pushes on the piston, driving motion of the piston, which is then converted into rotational energy of a crankshaft.
However, the inventors have recognized potential issues with such diesel engines. As one example, diesel fuel may not mix evenly with the air in the combustion chamber, leading to the formation of dense fuel pockets in the combustion chamber. These dense regions of fuel may produce soot as the fuel combusts. As such, conventional diesel engines include particulate filters for decreasing an amount of soot and other particulate matter in their emissions. However, such particulate filters lead to increased cost and increased fuel consumption.
Modern technologies for combating engine soot output include features for entraining air with the fuel prior to injection. This may include passages located in the injector body, as an insert into the engine head deck surface, or in engine head. Ambient air mixes with the fuel, cooling the injection temperature, prior to delivering the mixture to the compressed air in the cylinder. By entraining cooled air with the fuel prior to injection, a lift-off length is lengthened and start of combustion is retarded. This limits soot production through a range of engine operating conditions, reducing the need for a particulate filter.
However, the inventors herein have recognized potential issues with such injectors. As one example, the previously described fuel injectors may no longer sufficiently prevent soot production to a desired level in light of increasingly stringent emissions standards. As such, particulate filters may be located in an exhaust passage, thereby increasing a manufacturing cost and packaging restraint of the vehicle.
In one example, the issues described above may be addressed by a system comprising a fuel injector comprising a nozzle tip submerged into a combustion chamber below a cylinder head, the nozzle tip comprising one or more fuel injection orifices configured to inject at an angle relative to a central axis of the fuel injector and one or more mixing passages configured to receive a fuel injection or combustion chamber gases, where the one or more mixing passages configured to receive the fuel injection are oblique to the central axis and are aligned with the fuel injection orifices, and where the one or more mixing passages configured to receive combustion chamber gases include passage perpendicular to and parallel to the central axis, where the one or more mixing passage configured to receive the fuel injection are configured to receive combustion chamber gases from the one or more mixing passages configured to receive combustion chamber gases via one or more of a venturi passage and a louver. In this way, soot production is limited or prevented when pre-combustion is detected in the passage.
As one example, the mixing passages are integrated into one or more of a duct and nozzle tip of the fuel injector. First and second mixing passages of the mixing passages are configured to receive combustion chamber gases during a compression stroke of the cylinder. A third mixing passage receive the fuel injection and is configured to receive the combustion chamber gases from the first and second mixing passages via the venturi passage and/or louver. By mixing the fuel and air prior to releasing the fuel to the combustion chamber, the dense pockets of fuel described above may be avoided. A light sensor in the third mixing passage may determine if the mixture has combusted prior to flowing out of the passage to the engine. If this has occurred, then one or more engine operating parameters are adjusted to decrease a combustion chamber temperature. By doing this, a compact, and easy to manufacture duct and/or nozzle tip may decrease and/or prevent soot production during a wide range of engine operating conditions.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.